Purification process

ABSTRACT

This invention concerns a process for purifying crude oximes containing carbonyl and/or chlorine contaminants comprising treating said crude oximes with a basic reagent such as the metal oxides, carbonates and alcoholates of Groups IA and IIA of the Periodic Table to decompose the contaminants and separating the purified oxime from the impurities preferably by molecular distillation.

United States Patent Kuntschik et a1.

[ Oct. 9, 1973 PURIFICATION PROCESS [75] Inventorsf Lawrence F.Kuntschik, Nederland;

Orville W. Rigdon, Groves, both of Tex.

[52] U.S. Cl 260/566 A [51] Int. Cl. C07c 131/00 [58] Field of Search260/566 A [56] References Cited UNITED STATES PATENTS 2,562,205 7/1951Zlin et a1. 260/566 2,696,505 12/1954 Welz et a1... 260/566 2,721,21910/1955 Welz 260/566 2,822,394 2/1958 Nicolaisen et a1. 260/5662,885,332 5/1959 Mueller et a1. 204/158 3,197,505 7/1965 Jori 260/566Primary Examiner-Icon Zitver Assistant Examiner-Gerald A. SchwartzAttorney-K. E. Kavanagh and Thomas H. Whaley [57] ABSTRACT Thisinvention concerns a process for purifying crude oximes containingcarbonyl and/or chlorine contaminants comprising treating said crudeoximes with a basic reagent such as the metal oxides, carbonates andalcoholates of Groups 1A and 11A of the Periodic Table to decompose thecontaminants and separating the purified oxime from the impuritiespreferably by molecular distillation.

8 Claims, No Drawings l PURIFICATION PROCESS This process concerns aprocess for purifying crude oximes containing substantial quantities ofcarbonyl and/or chlorine contaminants by treatment with a basic reagent.

More particularly, this invention relates to a process wherein a crudeoxime product, derived from a photolytic nitrosation process if freedfrom substantial quantities of carbonyl-type and organic chlorineimpurities by contact with a basic reagent.

BACKGROUND OF THE INVENTION Oximes are useful as organic intermediatesand for various other applications. For example, they undergo theBeckmann rearrangement, can be alkoxylated and hydrogenated, and areuseful as lubrication additives, anti-icing additives and some oximescan be converted to synthetic fibers (i.e., cyclohexanone oxime can behydrolyzed into caprolactam, an intermediate for the commercialpreparation of Nylon 6).

Paraffinone oximes have been prepared by the base catalyzed reaction ofketones with hydroxylamine salts and more recently by the photolyticnitrosation of normal paraffins. Both of these synthetic methods canproduce a crude product which contains substantial quantities ofcontaminants boiling close to or overlapping the boiling points with theoxime product. Most of these impurities encountered in both processesare aldehydes or ketones (which are referred to generically ascarbonyl-type or impurities), while in the photolytic processgem-nitrosochlorides and gem-nitrosochloride condensation products canalso cause separation problems. In any event, conventional distillationpreceded or followed by extraction has failed to produce high purity(i.e., 98 percent or higher) products.

In view of the separation difficulties presented by these impuritiesthere is a need for a purification proce'-. dure directed to thepurification of paraffinone oximes containing substantial quantities ofcarbonyl-type and organic chlorine impurities, Particularly useful wouldbe a simple treatment which would utilize as starting material a crudeoxime product derived from the photolytic nitrosation of n-paraffinssuch as disclosed in Ser. No. 674,6l2 filed Oct. ll, 1967, now U.S. Pat.No. 3,578,575, and which contains substantial quantities ofcarbonyl-type and/or organic chlorine impurities. Desirably, thepurification procedure would utilize the 95 percent and lower oximecontent product of the above application and convert it to a product of98 percent and higher oxime content. Ideally, the novel process would berelatively inexpensive, would require no particular expertise and wouldutilize commercially available equipment.

OBJECTS OF THE INVENTION It is therefore an object of this invention topurify crude oximes containing substantial quantities of carbonyl-typeand organic chlorine impurities.

It is a more specific object of this invention to treat crude oximeproducts containing substantial quantities of carbonyl-type and/ororganic chlorine impurities so that the impurities are substantiallydecomposed.

The most specific object of this invention is to convert a crude oximeproduct of 95 percent or less oxime content, the residuum beingcarbonyl-type and organic chlorine impurities, to a highly purifiedoxime product ted.

of 98 percent and higher oxime content, substantially free fromcarbonyl-type and organic chlorine impurities.

The above objects are achieved by the novel process described below.

BRIEF DESCRIPTION OF THE INVENTION In practice, an oxime product,however derived, contaminated with substantial quantities ofcarbonyl-type and/or organic chlorine impurities is treated with a basicreagent until said impurities are decomposed and separating the purifiedoxime product from the decomposed impurities.

In the favored practice, a paraffinone oxime product containing fromfive to 30 or more carbon atoms, having an oxime content of 95 percentor less, and containing a substantial quantity of carbonyl-type andorganic chlorine impurities, is treated at ambient to elevatedtemperatures with anhydrous basic reagents, until the impurites aredecomposed, then separating the oxime from the decomposed contaminatingimpurities by moleculardistillation to produce an oxime substantiallyfree from said impurities.

In the preferred practice, a crude oxime product derived from thephotolytic nitrosation of n-paraffins, and containing from 10 to 15carbon atoms, said product having an oxime content of 95 percent orless, and containing up to 5 percent or more of carbonyl-type andorganic chlorine impurities, is first treated with from 1 to 20 percentby weight (based on the oxime content) of anhydrous base reagentselected from the group consisting of alkali metal and alkaline earthmetal carbonates and alkaline earth oxides, at near atmosphericpressures, at temperatures ranging from to 125 C. for 2 to 6 hours, tosubstantially decompose the impurities. Then inert solvent is added tothe base-treated oxime, to facilitate the separation of oxime (i.e., byfiltration, etc'.), and the oxime is separated from solids and Jdistilled under modecular distillation conditions sufficient to keep theconcentration of carbonyl-type and organic chlorine impurities fromsubstantially increasing.

DETAILED DESCRIPTION OF THE INVENTION In order to aid in theunderstanding of the inventive process, the following additionaldisclosure is submit- A; Paraffinone Oxime Product Any oxime,particularly paraffinone oxime products containing at least five carbonatoms up to 30 or more carbon atoms, can be utilized as charge stock aslong as it contains substantial quantities of carbonyletype and/ororganic chlorine impurities. The favored oximes are the linear andcyclic crude oximes such as the hexanone oximes, the cyclohexanoneoximes, the heptanone oximes, the octanone oximes the nonanone oximes,the decanone oximes, the undecanone oximes, the dodecanone oximes, theirhigher homologues and/or mixtures thereof. The preferred oximes arecrude cyclohexanone oxime and the paraffinone oximes containing 10 to 15carbon atoms of percent or less oxime content. They canbe in the form ofthe relatively dry, crude single oxime product, free from inert solvent,or as mixtures of the oximes having 10 to 15 carbon atoms, eitherrelatively free from solvent or containing up to 25 percent by weight ofinert solvent. The C to C group of oximes, whether solvent-free or not,are preferred because they are available in large quantities from thenitrosation of the corresponding paraffins as described in Ser. No.

674,612 Oct. 11, 1967.

B. Base The basic substances used in the novel treatment of thisinvention are the anhydrous oxides, hydroxides, carbonates andalcoholates, preferably of Groups IA and "A of the Periodic Table.lllustrative bases are calcium oxide, magnesium oxide, sodium carbonate,potassium carbonate, lithium carbonate, sodium hydroxide, potassiumhydroxide, sodium methoxide, sodium ethoxide, potassium methoxide,potassium ethoxide, and the like. The preferred basic reagents areselected from the anhydrous oxides and carbonates of the alkaline earthmetals and the anhydrous carbonates of the alkali metals. These basicreagents are employed at from 1 to 20 percent by weight concentrationlevels based upon the oxime content, preferably between 5 and percent.

C. Reaction Conditions 1. Temperature The reaction temperatures requiredfor the inventive process are relatively flexible, ranging from about 25to 200 C. In view of the fact that the best results have been obtainedbetween about 85 to 125 C., these temperatures represent the preferredrange.

2. Pressure Ordinarily atmospheric or near atmospheric pressures areemployed. Since no apparent advantage results from the use of superorsubatmospheric pressures and these pressures are more costly tomaintain, atmospheric pressures are preferred.

. Reaction Time The reaction time varies according to the reactiontemperature and concentration of base used, as well as the size of thebatch being treated, and for these reasons cannot be: defined precisely.However, under most conditions the reaction will be completed within 0.1and 12 hours of treatment with longer times no being harmful.

Under the more usual reaction conditions the reaction will be completewithin 2 to 6 hours.

4. Separation of Solid Materials The separation of solid materials maybe facilitated by the addition of one or more inert solvents to thereaction mixture. Ordinarly the inert solvent is added subsequent totreatment of the oxime with basic material to facilitate the removal (byfiltration, centrifugation, etc.) of solids. When inert solvent is addedat this time, any alkane, cycloalkane, arylalkane, aromatic, alcohol orketone that does not substantially dissolve the basic material may beemployed. The favored solvents are alkanes, cycloalkanes, alcoholscontaining five to 10 carbon atoms and ketones containing three to eightcarbon atoms. Acetone is the preferred inert solvent when addedsubsequent to base treatment. If it is desired to add the inert solventprior to the treatment with base, then only hy drocarbon solvents suchas alkanes,-cycloalkanes, arylalkanes or aromatics should be employed.In any event, the inert solvent should be removed prior to thedistillation under high vacuum."

D. Process Conditions As described supra, the'gist of this invention isthe discovery, that the oxime content of crude oximescan besubstantially '-increased with a corresponding decrease in carbonyl typeand organic chlorine impurities by treating the crude oxime with certainanhydrous or substan-" tially anhydrous basic substances. This isparticu-' larly the case of crude oximes containing percent or lessoxime content, which are derived from the photolytic nitrosation of thecorresponding nparaffins. Peculiarly enough, while the inventivetreatment results in an increase of 98 percent of greater oxime contentwith a carbonyl-type plus organic chlorine impurities totaling less than2 percent, this increase in purity and decrease in impurities cannot bemaintained if the separation of oxime from impurities is done usingconventional vacuum distillation even as low as 0.4 to 2.0 mm ofmercury. However, when the purified, treated and filtered oxime productis distilled using molecular distillation techniques such as continuousfilm vacuum distillation (CFD), the purity and impurity level remainssubstantially unchanged. For this reason, the preferred aspect of thisinvention comprises: Contacting the neutralized crude oxime containing95 percent'or less oxime content with five to 10 percent by weight ofanhydrous basic reagent (based upon oxime content) selected from thegroup consisting of alkaline earth metal oxides and carbonates andalkali metal carbonates, for 2 to 6 hours at 85 to C. to substantiallydecompose the aforementioned impurities, then 2. Adding inert solventand separating solid material by filtration, centrifugation and thelike, removing inert solvent, then 3. Subjecting the clarifiedoxime-decomposed impu rities mixture to continuous film vacuumdistillation under conditions sufficient to substantially retain theconcentration level of carbonyl-type and organic chlorine impuritiesunchanged.

E. sufficiently Mild Vacuum as described previbeen obtained usingmolecular distillation tech-. niques and for this reason thesetechniques are favored. Molecular distillations as used herein refers tothose distillation means where the vapor path of the molecules beingdistilled is unobstructed and the condenser in the apparatus isseparated from the evaporation by a distance less the mean free path ofthe evaporating, emerging molecules. While molecular distillationtechniques are favored, as is frequently the case where a broad class isemployed, a more specific technique or process within the broad class ispreferred for one reason or another. In the instant case, distillationwithin a molecular'pot still is preferred since it preserves the lowcontaminant level of the treated oxime substantially unchanged. Thesetype of distillations can be carried out in a variety of apparatus atvacuurns ranging from 0.001 to 0.0001 mm of mercury.

Two types of commercially available molecular stills which are widelyused employ either centrifu- ..,;.gal or continuous (or falling) filmtechniques. Illus- ;-"tr ative stills are described in detail in Chapter17,

pages 29-32, of the Chemical Engineering Handbook by Perry, Chilton andKirkpatrick, 4th Edition, published by McGraw Hill Inc., New York, N.Y., among other publications.

Having described the inventive process in general terms, the followingexamples and embodiments are submitted to supply more detailedillustrations of its workings.

Embodiment A Preparation of a Crude Mixed C -C Paraffinone Oxime ProductContaining Substantial Quantities of Carbonyl-Type Impurities:

A 22.981 kg portion of mixed C -C n-paraffins is charged to aphotoreactor equipped with heating and cooling means and a means ofdirecting a light source with excludes wave lengths below 200millimicrons. The paraffin mixture is reacted with excess of gaseousnitrosyl chloride at 60 F. in the presence of gaseous hydrogen chlorideat flow rates of 1.64 grams per minute and 0.95 grams per minute,respectively. After separation of the crude oxime-acid salt, the acidwas neutralized with aqueous ammonia and the crude C -C oxime mixture isseparated. The molar selectivity to crude oximes was 87.4 percent withan overall recovery of 90.7 percent by weight oxime. The crude oximeproduct contained about 2 percent by weight of C -C, ketones.

Example 1 Attempted Purification of Neutralized Crude C -C n-ParaffinoneOxime Mixture Using Conventional Vacuum Distillation:

An 800-gram crude mixture ofC, C n-paraffinone oxime prepared as inEmbodiment A and containing 4.3 percent by weight of ketones and 0.41percent by weight chlorine is batch vacuum fractionated at 0.4 to 0.6 mmof mercury on an 18 inches Hempel column packed with 1/4 inch protrudedstainless steel packing in the presence of 100.0 grams of 700 F.hydrocarbon chaser. The following summarizes the results:

As the increase in ketones 175 percent by weight increase) indicates,conventional vacuum distillation without treatment by basic reagentsworsens the purity of oxime product. The distillate product exhibited ahazy appearance.

Example 2 Attempted Purification of Crude C -C n-Paraffinone OximeMixture Using Continuous Thin Film Distillation Without a PrecedingTreatment with Base:

A 90 gram portion of crude C, C, paraffinone oxime prepared as inEmbodiment A andcontaining 3.6 percent by weight of ketones and 1.15percent by weight of chlorine, is charges to a 2 inches Rodney HuntVaca-Film Processor sold by Rodney Hunt Machine Co. (currently sold byArthur F. Smith Co.), and heated to 100 to 105 C. at 0.3 mm Hg pressure.A light colored oxime distillate (67.0 grams) containing 2.6 percent byweight of ketones and 0.93 percent by weight of chlorine is obtained.The product exhibited an undesirable hazy appearance.

This example demonstrates that without the novel preceding basetreatment, continuous thin film distillation is not an effective meansof substantially removing carbonyl-type and organic chlorine impuritiesfrom the neutralized crude oxime.

Example 3 Substantial Reduction of Carbonyl- Type and Organic ChlorineImpurities Contained in Crude Mixtures of C C Paraffinone Oximes Usingthe Preferred Process Wherein Anhydrous Calcium Oxide is the BasicReagent:

A 500 gram mixture of C -C paraffinone oximes prepared as in EmbodimentA, containing 2.0 percent by weight of ketones and 0.51 percent byweight of chlorine is thoroughly mixed with grams of anhydrous calciumoxide in a reaction vessel heated to 100 C. for 2 hours. After vacuumfiltration, the oximes (435 grams) contained less than 0.5 percent byweight of ketones, and 0.42 percent by weight of organic chlorine. Thissubstantial reduction of impurities is illustrative of the efficacy ofthe inventive base treatment.

The calcium oxide-treated oxime mixture is exposed to continuous filmdistillation at 98 to 100 C. at 0.4 mm of mercury on the apparatusdescribed in Example 2. A light colored oxime mixture (69 grams)containing less than 0.5 percent by weight of ketone and 0.23 percent byweight chlorine is obtained. This example demonstrates the efficacy ofthe preferred process in substantially reducing impurity content as wellas the use of alkaline earth metal treating agents as the basicreagents.

The same results as obtained using a centrifugal-type molecular still. 7

Example 4 Substantial Reduction of Carbonyltype and Organic ChlorineImpurities Using the Preferred Process Wherein Anhydrous SodiumCarbonate is Employed as the Basic Reagent:

A 500 gram portion of crude C l4 C n-paraffinone oximes prepared asdescribed in Example 1 and containing 2.3 percent by weight of ketonesand 0.93 percent by weight of chlorine are thoroughly mixed with 100grams of anhydrous Na CO at 100 C. for 2 hours.

-The purified oxime (406.5 grams) obtained after vacuum filtrationcontained less than 1 percent by weight of ketone and 0.78 percent byweight of organic chlorine.

After thin film distillation in the apparatus of Examples 2 and 3 at 100to C. at 0.15 to 0.35 mm Hg pressure, a light colored oxime (307.6grams) is produced that contains less than 1 percent by weight of ketoneand 0.41 percent by weight of chlorine.

This example demonstrates that anhydrous alkali metal carbonates areeffective base treating reagents.

Example 5 Substantial Reduction of Carbonyl- Type and Organic ChlorineImpurities Using the Preferred Process Wherein Inert Solvent isUtilized:

A 500 gram portion of a neutralized crude C -C oxime mixture prepared asin Embodiment A, containing 2.3 percent by weight of ketone and 0.93percent by weight of chlorine is mixed as before with 25 grams ofanhydrous calcium oxide and heated to 100C. for 2 hours. After cooling,the reaction mixture is diluted with 1,300 grams of mixed heptanes andwashed three times with equal volumes of water. The solution is filteredand stripped in vacuum of the heptanes. An

oxime product (376 grams) is obtained substantially free from ketonecontamination.

A 6.8 gram portion of the treated oxime is distilled on a continuousthin film distilling apparatus at 100 to C. at 0.25 mm Hg pressureproducing a light colored oxime substantially free of ketonecontaminants.

This example demonstrates the use of the preferred process in thepresence of large quantities of inert solvent.

Example 6 The Process of Example Wherein the Reaction Mixture is Dilutedwith inert Solvent Prior to Filtration:

The procedure of Example 5 is followed except that 25 grams of Na CO ismixed with 500 grams of the same crude C -C oxime, and one liter of theheptanes is added prior to filtration. The initial ketone concentrationis reduced from 2.3 percent by weight to less than 1 percent by weightand chlorine from 0.93 to 0.55 percent by weight chlorine. Continuousthin film distillation of 341.9 grams at 100 to 105 C. at 0.2 to 0.3 mmof Hg on the preceding examples apparatus yields a light colored oxime(2.98.4 grams) containing less than 1 percent by weight ketones and 0.42percent by weight chlorine.

Example 7 Repeat of the Procedure of Example 6 Utilizing Cyclohexane asInert Solvent Prior to Filtration:

In this example 500 grams of the neutralized C -C oxime mixture ofExample 5 is heated with 25 grams of anhydrous Na CO for 3 hours at 100C. After cooling as in Example 5, the reaction mixture is diluted with 1liter of cyclohexane and filtered. The solvent is stripped off undervacuum leaving an oxime product (417 grams) containing less than 1percent by weight ketone (compared to an original 2 to 3 percent byweight) and 0.51 percent by weight chlorine (compared to an original0.93 percent by weight concentration). The stripped oxime mixture isdistilled on the CFD apparatus previously alluded to at 100 to 105 C. at0.2 to 0.3 mm Hg pressure to produce 220.9 grams of distillatecontaining less than 1 percent by weight ketone.

Example 8 Repeat of Example 7 Using Acetone as lnert Diluent:

In this example 500 grams of a crude neutralized mixture of C -Cn-paraffinone oximes containing 2.6 percent by weight of ketone and 1.05percent by weight of organic chlorine is heated with 50 grams ofanhydrous Na CO at 100 C. for 4 hours. The mixture is diluted with 1liter of acetone, filtered and stripped of acetone under vacuum toproduce 428 grams ofa treated product containing less than 1 percent byweight of ketones and 0.91 percent by weight of organic chlorine.

Using the CFD unit previously described, a 158.8 gram portion of thetreated oxime misture is distilled at 95 to 115 C. at 0.05 to 0.1 mm Hgpressure to produce a light colored oxime (139.3 grams) containing lessthan 1.0 percent by weight of ketones and 0.80 percent by weight ofchlorine.

Example 9 Vacuum Fractional Distillation of the Base-treated OximeMixture of Example 8:

A 210 gram portion of the filtered base-treated oxime mixture preparedin Example 8 is fractionated in the apparatus described in Example 1,giving the'following results:

Fraction No. l 2 3 Boiling Point, C. 105 118 137 Pressure, mm Hg 1.351.65 1.55 Weight, grams 9.0 144.5 32.5 Ketones in Fraction, Wt. 20 1.08.4

The above data indicates that conventional vacuum ketone and chlorinecontent not only fails to retain the decrease in impurities previouslyobtaining but actually increases the impurities to more than 184 percentby weight compared to the base-treated oxime. This illustrates the needfor both base treatment and a heatsensitive separation step.

Embodiment B Preparation of a Specific Oxime Containing SubstantialQuantities of Carbonyl-Type Impurities:

Using the general procedure described in Sedgwick, Organic Chemistry ofNitrogen, pages 169-175 (1937 edition), 1.2 moles of diethyl ketone isreacted with a water solution of 1 mole of hydroxylamine at roomtemperature to produce 0.8 moles of diethyl ketoxime,

THIGH CH CH CCH CH contaminated with 3.5 percent diethyl ketone.

Example 10 Purification of a Specific Paraffinone Oxime ContainingSubstantial Quantities of Carbonyl- Type impurities:

The 0.8 mole portion of diethyl ketoxime prepared in Embodiment B isthoroughly mixed with 10 grams of anhydrous calcium oxide and heated at105 C. for 4 hours. The reaction mixture is filtered and is found tocontain less than 1 percent by weight of ketone. After continuous filmdistillation at to 110 C. at 0.5 to 0.6 mm of mercury, the ketoneconcentration remains at less than 1 percent by weight of ketone. Thisexample demonstrates:

1. That the novel process is applicable to crude specific oximes ratherthan only to mixtures, and

2. That the process is operable upon oxime substrates derived from otherthan photolytic nitrosation procedures.

As the several examples have indicated, the novel process offers severaladvantages compared to the prior art. For example, the inventivepurification procedure provides a means of purifying and upgrading crudeoximes and their mixtures containing substantial carbonyl-type andorganic chlorine impurities. In addition, the process is simple andinexpensive and uses commonplace reagents. Further, the process offersthe first practical method of converting crude mixtures of C to C oximeshaving an initial oxime content of less than percent oxime to 98 percentand higher oxime content with a corresponding decrease in saidimpurities.

Surprisingly enough, not only does the inventive process substantiallyreduce the amount of carbonyl-type and chlorine impurities contaminatingthe oxide product, but the sequence of steps is critical. That is, if inthe preferred process continuous thin film distillation precedestreatment of base, relatively little reduction in impurities results. Incontrast, base treatment of the oxime followed by continuous thin filmdistillation (or an equivalent separation system) results in a permanentand substantial reduction in said impurities. A further unexpectedaspect of this invention is that if base treatment of the oxime isfollowed by conventional vacuum distillation, albeit even at lowvacuums, i.e., 0.2 to 0.4 mm of mercury, a substantial increase ofcontaminants beyond pre-treatment levels is observed.

As indicated above, except for the sequence of steps,

1 the inventive process allows various modifications, subdistillation ofa base-treated oxime batch with reduced stitutions and changes to bemade in reaction conditions, type of base, etc., without departing fromthe inventive concept. The metes and bounds of this invention are bestdetermined by the claims which follow read in conjunction with thespecification.

What is claimed is:

l. A process for substantially increasing the oxime content of crudeparaffinone oxime product derived from the photolytic nitrosation ofn-paraffins containing from to carbon atoms, said crude oximescontaining at least 5 percent by weight of carbonyl-type and organicchlorine impurities, comprising the steps of:

a. treating said oxime product with a substantially anhydrous basicreagent selected from the group consisting of oxides of alkaline earthmetals and carbonates of alkali metals and alkaline earth metals, attemperatures ranging from 25 to 200 C., said basic reagent being presentto the extent of l to percent by weight of the oxime content, until saidimpurities are decomposed,

b. separating insoluble materials from the treated oxime product, and

c. separating the treated oxime from decomposed carbonyl-type andorganic-type impurities by exposing said oxime to continuous thin filmdistillation until an oxime product of substantially increased oximecontent is produced.

2. The process of claim 1 wherein inert solvent is added to the reactionmixture after the impurities are decomposed and separation from solidsis accomplished by filtration.

3. The process of claim 1 wherein the treatment with basic reagent iscarried out between 85 and 125 C.

4. The process of claim 3 wherein the basic reagent is calcium oxide.

5. The process of claim 3 wherein the basic reagent is sodium carbonate.

6. The process of claim 3 wherein the original oxime content of thecrude product is less than percent oxime.

7. The process of claim 6 wherein the treated product has a 98 percentand higher oxime content.

8. A process for purifying preformed crude paraffinone oxime containing95 percent or less of cyclohexanone oxime and a mixture of paraffinoneoxime, said paraffinone oximes having a carbon content of 10 to 15carbon atoms and containing at least 5 percent of impurities selectedfrom the group consisting of ketones, aldehydes and organic chlorenecompounds, said crude oximes being derived from the photolyticnitrosation of mixtures of n-paraffins containing from IO-to 15 carbonatoms, comprising the steps of:

a. treating said crude preformed paraffinone oximes at 85 to C for 2 to6 hours with 5 to 10 percent by weight of anhydrous basic reagentselected I product is produced.

2. The process of claim 1 wherein inert solvent is added to the reactionmixture after the impurities are decomposed and separation from solidsis accomplished by filtration.
 3. The process of claim 1 wherein thetreatment with basic reagent is carried out between 85* and 125* C. 4.The process of claim 3 wherein the basic reagent is calcium oxide. 5.The process of claim 3 wherein the basic reagent is sodium carbonate. 6.The process of claim 3 wherein the original oxime content of the crudeproduct is less than 95 percent oxime.
 7. The process of claim 6 whereinthe treated product has a 98 percent and higher oxime content.
 8. Aprocess for purifying preformed crude paraffinone oxime containing 95percent or less of cyclohexanone oxime and a mixture of paraffinoneoxime, said paraffinone oximes having a carbon content of 10 to 15carbon atoms and containing at least 5 percent of impurities selectedfrom the group consisting of ketones, aldehydes and organic chlorenecompounds, said crude oximes being derived from the photolyticnitrosation of mixtures of n-paraffins containing from 10 to 15 carbonatoms, comprising the steps of: a. treating said crude preformedparaffinone oximes at 85* to 125* C for 2 to 6 hours with 5 to 10percent by weight of anhydrous basic reagent selected from the groupconsisting of calcium oxide and sodium carbonate, said weight of basicreagent being based upon the paraffinone oxime content, to substantiallydecompose said impurities, b. adding inert solvent to the basicreagent-treated paraffinone oxime to precipitate solid material from thesolution of oximes containing decomposed impurities, c. clarifying saidoxime solution by filtration to produce a clarified oxime solutioncontaining said decomposed impurities, and d. subjecting the clarifiedoxime solution containing decomposed impurities to continuous thin filmvacuum distillation until a substantially purified oxime product isproduced.